Water-dispersible fibers and fibrous articles

ABSTRACT

Disclosed are water-dispersible fibers derived from sulfopolyesters having a Tg of at least 25° C. The fibers may contain a single sulfopolyester or a blend of a sulfopolyester with a water-dispersible or water-nondispersible polymer. Also disclosed are fibrous articles from the water-dispersible fibers. The fibrous articles include water-dispersible nonwoven webs, fabrics, and multilayered articles such as wipes, gauze, tissue, diapers, panty liners, sanitary napkins, bandages, and surgical dressings. Also disclosed is a process for water-dispersible fibers and nonwoven fabrics. The fibers and fibrous articles have further applications in flushable personal care and cleaning products, disposable protective outerwear, and laminating binders.

FIELD OF THE INVENTION

[0001] The present invention pertains to water-dispersible fibers and fibrous articles. More specificially, the present invention pertains to water-dispersible fibers and articles thereof comprising a sulfopolyester. The invention further pertains to a process for water-dispersible fibers and nonwoven fabrics. The fibers and fibrous articles have applications in flushable personal care products, medical products, and laminating binders.

BACKGROUND OF THE INVENTION

[0002] Fibers, melt blown webs and other melt spun fibrous articles have been made from thermoplastic polymers, such as polypropylene and polyesters. One common application of these fibers and fibrous articles are nonwoven fabrics and, in particular, in personal care products such as wipes, feminine hygiene products, baby diapers, adult incontinence briefs, hospital/surgical and other medical disposables, protective fabrics and layers, geotextiles, and filter media. Unfortunately, the personal care products mades from conventional thermoplastic polymers are difficult to dispose of and are usually placed in landfills. One promising alternative method of disposal is to make these products or their components “flushable”, i.e., compatible with public sewerage systems. The use of water-dispersible or water-soluble materials also improves recyclability and reclamation of personal care products. The various thermoplastic polymers now used in personal care products are not inherently water-dispersible or soluble and, hence, do not produce articles that readily disintegrate and can be disposed of in a sewerage system or recycled easily.

[0003] The desirability of flushable personal care products has resulted in a need for fibers, nonwovens, and other fibrous articles with various degrees of water-responsivity. Various approaches to addressing these needs have been described, for example, in U.S. Pat. Nos. 6,548,592; 6,552,162; 5,281,306; 5,292,581; 5,935,880; and 5,509,913; U.S. patent application Ser. Nos. 09/775,312; and 09/752,017; and PCT International Publication No. WO 01/66666 A2. These approaches, however, suffer from a number of disadvantages and do not provide a fibrous article, such as a fiber or nonwoven fabric, that possesses a satisfactory balance of performance properties, such as tensile strength, absorptivity, flexibility, and fabric integrity under both wet or dry conditions.

[0004] For example, typical nonwoven technology is based on the multidirectional deposition of fibers that are treated with a resin binding adhesive to form a web having strong integrity and other desirable properties. The resulting assemblies, however, generally have poor water-responsivity and are not suitable for flushable applications. The presence of binder also may result in undesirable properties in the final product, such as reduced sheet wettability, increased stiffness, stickiness, and higher production costs. It is also difficult to produce a binder that will exhibit adequate wet strength during use and yet disperse quickly upon disposal. Thus, nonwoven assemblies using these binders may either disintegrate slowly under ambient conditions or have less than adequate wet strength properties in the presence of body fluids. To address this problem, pH and ion-sensitive water-dispersible binders, such as lattices containing acrylic or methacrylic acid with or without added salts, are known and described, for example, in U.S. Pat. No. 6,548,592 BI. Ion concentrations and pH levels in public sewerage and residential septic systems, however, can vary widely among geographical locations and may not be sufficient for the binder to become soluble and disperse. In this case, the fibrous articles will not disintegrate after disposal and can clog the drain or sewer lateral. Multicomponent fibers containing a water-dispersible component and a thermoplastic component have been described, for example, in U.S. Pat. No. 5,916,678, where the water-dispersible component also serves as a bonding agent for the thermoplastic fibers in nonwoven webs. Upon exposure to water, the fiber to fiber bonds come apart such that the nonwoven web loses its integrity and breaks down into individual fibers. The thermoplastic fiber components of these nonwoven webs, however, are not water-dispersible and remain present in the aqueous medium and, thus, must eventually be removed from municipal wastewater treatment plants. Hydroentanglement may be used to produce disintegratable nonwoven fabrics without or with very low levels (<5 wt %) of added binder to hold the fibers together. Although these fabrics may disintegrate upon disposal, they often utilize fibers that are not water soluble or water-dispersible and may result in entanglement and plugging within sewer systems.

[0005] A few water-soluble or water-dispersible polymers are available, but are generally not applicable to melt blown fiber forming operations or melt spinning in general. Polymers, such as polyvinyl alcohol, polyvinyl pyrrolidone, and polyacrylic acid are not melt processable as a result of thermal decomposition that occurs at temperatures below the point where a suitable melt viscosity is attained. High molecular weight polyethylene oxide may have suitable thermal stability, but would provide a high viscosity solution at the polymer interface resulting in a slow rate of disintegration. Water-dispersible sulfopolyesters have been described, for example, in U.S. Pat. Nos. 6,171,685; 5,543,488; 5,853,701; 4,304,901; 6,211,309; 5,570,605; 6,428,900; and 3,779,993. Typical sulfopolyesters, however, are low molecular weight thermoplastics that are brittle and lack the flexibility to withstand a winding operation to yield a roll of material that does not fracture or crumble. Low molecular weight polyethylene oxide (more commonly known as polyethylene glycol) is a weak/brittle polymer that also does not have the required physical properties for fiber applications. Forming fibers from known water-soluble polymers via solution techniques is an alternative, but the added complexity of removing solvent, especially water, increases manufacturing costs.

[0006] Accordingly, there is a need for a water-dispersible fiber and fibrous articles prepared therefrom that exhibit adequate tensile strength, absorptivity, flexibility, and fabric integrity in the presence of moisture, especially upon exposure to human bodily fluids. In addition, a fibrous article is needed that does not require a binder and completely disperses or dissolves in residential or municipal sewerage systems. Potential uses include, but are not limited to, melt blown webs, spunbond fabrics, bicomponent fiber components, adhesive promoting layers, binders for cellulosics, flushable nonwovens and films, dissolvable binder fibers, protective layers, and carriers for active ingredients to be released or dissolved in water. Other extrudable and melt spun fibrous materials are also possible.

SUMMARY OF THE INVENTION

[0007] We have unexpectedly discovered that flexible, water-dispersible fibers may be prepared from sulfopolyesters. Thus the present invention provides a water-dispersible fiber comprising:

[0008] (A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfpolyester comprising:

[0009] (i) residues of one or more dicarboxylic acids;

[0010] (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof;

[0011] (iii) one or more diol residues wherein at least 25 mole %, based on the total hydroxyl residues, is a poly(ethylene glycol) having a structure

H—(OCH2—CH2)n—OH

[0012]  wherein n is an integer in the range of 2 to about 500; and

[0013] (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof;

[0014] (B) optionally, a water-dispersible polymer blended with said sulfopolyester; and

[0015] (C) optionally, a water-nondispersible polymer blended with said sulfopolyester with the proviso that said blend is an immiscible blend.

[0016] The fibers of the present invention are unicomponent fibers that rapidly disperse or dissolve in water and may be produced by melt-blowing or melt-spinning. The fibers may be prepared from a single sulfopolyester or a blend of the sulfopolyester with a water-dispersible or water-nondispersible polymer. Thus, the fiber of the present invention, optionally, may include a water-dispersible polymer blended with the sulfopolyester. In addition, the fiber may optionally include a water-nondispersible polymer blended with the sulfopolyester, provided that the blend is an immiscible blend. Our invention also includes fibrous articles comprising our water-dispersible fibers. Thus, the fibers of our invention may be used to prepare various fibrous articles, such as yarns, melt-blown webs, spunbonded webs, and nonwoven fabrics that are, in turn, water-dispersible or flushable.

[0017] Another aspect of the present invention is a water-dispersible fiber comprising:

[0018] A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfopolyester comprising:

[0019] (i) about 50 to about 96 mole % of a residue of isophthalic acid, based on the total acid residues;

[0020] (ii) about 4 to about 30 mole %, based on the total acid residues, of a residue of sodiosulfoisophthalic acid;

[0021] (iii) one or more diol residues wherein at least 25 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure

H—(OCH2—CH2)n—OH

[0022]  wherein n is an integer in the range of 2 to about 500;

[0023] (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof;

[0024] (B) optionally, a first water-dispersible polymer blended with said sulfopolyester; and

[0025] (C) optionally, a water-nondispersible polymer blended with said sulfopolyester to form a blend with the proviso that said blend is an immiscible blend.

[0026] The water-dispersible, fibrous articles of the present invention include personal care articles such as, for example, wipes, gauze, tissue, diapers, training pants, sanitary napkins, bandages, wound care, and surgical dressings. In addition to being water-dispersible, the fibrous articles of our invention are flushable, that is, compatible with and suitable for disposal in residential and municipal sewerage systems.

[0027] Our invention also provides a process for a process for water-dispersible, nonwoven fabric comprising:

[0028] I. providing a water-dispersible polymer composition comprising

[0029] (A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfopolyester comprising:

[0030] (i) residues of one or more dicarboxylic acids;

[0031] (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more metal sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof;

[0032] (iii) one or more diol residues wherein at least 20 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure

H—(OCH2—CH2)n—OH

[0033]  wherein n is an integer in the range of 2 to about 500;

[0034] (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof;

[0035] (B) optionally, a water-dispersible polymer blended with said sulfopolyester; and

[0036] (C) optionally, a water-nondispersible polymer blended with said sulfopolyester to form a blend with the proviso that said blend is an immiscible blend.

[0037] II. heating said polymer composition to a temperature above its flow point;

[0038] III. melt spinning filaments; and

[0039] IV. overlapping and collecting said filaments of Step III to form a nonwoven web.

[0040] Our invention thus offers a novel and inexpensive process for a water-dispersible nonwoven fabric by melt-spinning a water-dispersible sulfopolyester and forming a nonwoven web. The nonwoven fabric may be in the form of a flat fabric or a 3-dimensional shape and may be incorporated into a variety of fibrous articles such as the personal care articles noted hereinabove or used for the manufacture of water-dispersible and/or flushable protective outerware such as, for example, surgical gowns and protective clothing for chemical and biohazard cleanup and laboratory work.

DETAILED DESCRIPTION

[0041] The present invention provides water-dispersible fibers and fibrous articles that show tensile strength, absorptivity, flexibility, and fabric integrity in the presence of moisture, especially upon exposure to human bodily fluids. In addition, the fibrous articles prepared from our novel fibers do not require a binder and readily disperse or dissolve in home or public sewerage systems. In a general embodiment, our invention provides a water-dispersible fiber comprising a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., wherein the sulfpolyester comprises: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; (iii) one or more diol residues wherein at least 25 mole %, based on the total hydroxyl residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0042] wherein n is an integer in the range of 2 to about 500; and (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof. Our fiber may optionally include a water-dispersible polymer blended with the sulfopolyester and, optionally, a water-nondispersible polymer blended with the sulfopolyester with the proviso that the blend is an immiscible blend. The present invention also includes fibrous articles comprising these fibers and may include personal care products such as wipes, gauze, tissue, diapers, adult incontinence briefs, training pants, sanitary napkins, bandages, and surgical dressings. The fibrous articles may have one or more absorbent layers of fibers. The fibers of our invention are unicomponent fibers, as opposed to bicomponent or multicomponent fibers; that is, the fibers of the present invention are prepared by melt spinning a single sulfopolyester or sulfopolyester blend and include staple, monofilament, and multifilament fibers with a shaped cross-section. By contrast, multicomponent fibers, such as described, for example, in U.S. Pat. No. 5,916,678, are prepared by extruding two polymers separately. The polymers are fed to a polymer distribution system where the polymers are introduced into a segmented spinneret plate. The polymers follow separate paths to the fiber spinneret and are combined at the spinneret hole which comprises either two concentric circular holes thus providing a sheath/core type fiber or a circular spinneret hole divided along a diameter into two parts to provide a side-by-side type fiber.

[0043] Unless otherwise indicated, all numbers expressing quantities of ingredients, properties such as molecular weight, reaction conditions, and so forth used in the specification and claims are to be understood as being modified in all instances by the term “about.” Accordingly, unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, each numerical parameter should at least be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Further, the ranges stated in this disclosure and the claims are intended to include the entire range specifically and not just the endpoint(s). For example, a range stated to be 0 to 10 is intended to disclose all whole numbers between 0 and 10 such as, for example 1, 2, 3, 4, etc., all fractional numbers between 0 and 10, for example 1.5, 2.3, 4.57, 6.1113, etc., and the endpoints 0 and 10. Also, a range associated with chemical substituent groups such as, for example, “C1 to C5 hydrocarbons”, is intended to specifically include and disclose C1 and C5 hydrocarbons as well as C2, C3, and C4 hydrocarbons.

[0044] Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contain certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

[0045] The fibers and fibrous articles of the present invention are water-dispersible and, typically, completely disperse at room temperature. The term “water-dispersible”, as used herein, is intended to be synonymous with the terms “water-dissipatable”, “water-disintegratable”, “water-dissolvable”, “water-dispellable”, “water soluble”, “hydrosoluble”, and “hydrodispersible” and is intended to mean that the fiber or fibrous article is therein or therethrough dispersed or dissolved by the action of water. The terms “dispersed”, “dispersible”, “dissipate”, or “dissipatable” mean that, using a sufficient amount of deionized water (e.g., 100:1 water:fiber by weight) to form a loose suspension or slurry of the fibers or fibrous article, at a temperature of about 60° C., and within a time period of up to 5 days, the fiber or fibrous article dissolves, disintegrates, or separates into a plurality of incoherent pieces or particles distributed more or less throughout the medium such that no recognizable filaments are recoverable from the medium upon removal of the water, for example, by filtration or evaporation. Thus, “water-dispersible”, as used herein, is not intended to include the simple disintegration of an assembly of entangled or bound, but otherwise water insoluble or nondispersible, fibers wherein the fiber assembly simply breaks apart in water to produce a slurry of fibers in water which could be recovered by removal of the water. In the context of this invention, all of these terms refer to the activity of water or a mixture of water and a water-miscible cosolvent on the sulfopolyesters described herein. Examples of such water-miscible cosolvents includes alcohols, ketones, glycol ethers, esters and the like. It is intended for this terminology to include conditions where the sulfopolyester is dissolved to form a true solution as well as those where the sulfopolyester is dispersed within the aqueous medium. Often, due to the statistical nature of sulfopolyester compositions, it is possible to have a soluble fraction and a dispersed fraction when a single sulfopolyester sample is placed in an aqueous medium.

[0046] The water-dispersible fiber of the present invention is prepared from polyesters or, more specifically sulfopolyesters, comprising dicarboxylic acid monomer residues, sulfomonomer residues, diol monomer residues, and repeating units. The sulfomonomer may be a dicarboxylic acid, a diol, or hydroxycarboxylic acid. Thus, the term “monomer residue”, as used herein, means a residue of a dicarboxylic acid, a diol, or a hydroxy-carboxylic acid. A “repeating unit”, as used herein, means an organic structure having 2 monomer residues bonded through a carbonyloxy group. The sulfopolyesters of the present invention contain substantially equal molar proportions of acid residues (100 mole %) and diol residues (100 mole %) which react in substantially equal proportions such that the total moles of repeating units is equal to 100 mole %. The mole percentages provided in the present disclosure, therefore, may be based on the total moles of acid residues, the total moles of diol residues, or the total moles of repeating units. For example, a sulfopolyeseter containing 30 mole % of a sulfomonomer, which may be a dicarboxylic acid, a diol, or hydroxycarboxylic acid, based on the total repeating units, means that the sulfopolyester contains 30 mole % sulfomonomer out of a total of 100 mole % repeating units. Thus, there are 30 moles of sulfomonomer residues among every 100 moles of repeating units. Similarly, a sulfopolyeseter containing 30 mole % of a dicarboxylic acid sulfomonomer, based on the total acid residues, means the sulfopolyester contains 30 mole % sulfomonomer out of a total of 100 mole % acid residues. Thus, in this latter case, there are 30 moles of sulfomonomer residues among every 100 moles of acid residues.

[0047] The sulfopolyesters described herein have an inherent viscosity, abbreviated hereinafter as “Ih.V.”, of at least about 0.1 dL/g, preferably about 0.2 to 0.3 dL/g, and most preferably greater than about 0.3 dL/g, measured in a 60/40 parts by weight solution of phenol/tetrachloroethane solvent at 25° C. and at a concentration of about 0.5 g of sulfopolyester in 100 mL of solvent. The term “polyester”, as used herein, encompasses both “homopolyesters” and “copolyesters” and means a synthetic polymer prepared by the polycondensation of difunctional carboxylic acids with difunctional hydroxyl compound. As used herein, the term “sulfopolyester” means any polyester comprising a sulfomonomer. Typically the difunctional carboxylic acid is a dicarboxylic acid and the difunctional hydroxyl compound is a dihydric alcohol such as, for example glycols and diols. Alternatively, the difunctional carboxylic acid may be a hydroxy carboxylic acid such as, for example, p-hydroxybenzoic acid, and the difunctional hydroxyl compound may be a aromatic nucleus bearing 2 hydroxy substituents such as, for example, hydroquinone. The term “residue”, as used herein, means any organic structure incorporated into the polymer through a polycondensation reaction involving the corresponding monomer. Thus, the dicarboxylic acid residue may be derived from a dicarboxylic acid monomer or its associated acid halides, esters, salts, anhydrides, or mixtures thereof. As used herein, therefore, the term dicarboxylic acid is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, mixed anhydrides, or mixtures thereof, useful in a polycondensation process with a diol to make a high molecular weight polyester.

[0048] The sulfopolyester of the present invention includes one or more dicarboxylic acid residues. Depending on the type and concentration of the sulfomonomer, the dicarboxylic acid residue may comprise from about 60 to about 100 mole % of the acid residues. Other examples of concentration ranges of dicarboxylic acid residues are from about 60 mole % to about 95 mole %, and about 70 mole % to about 95 mole %. Examples of dicarboxylic acids that may be used include aliphatic dicarboxylic acids, alicyclic dicarboxylic acids, aromatic dicarboxylic acids, or mixtures of two or more of these acids. Thus, suitable dicarboxylic acids include, but are not limited to succinic; glutaric; adipic; azelaic; sebacic; fumaric; maleic; itaconic; 1,3-cyclohexanedicarboxylic; 1,4-cyclo-hexanedicarboxylic; diglycolic; 2,5-norbornanedicarboxylic; phthalic; terephthalic; 1,4-naphthalenedicarboxylic; 2,5-naphthalenedicarboxylic; diphenic; 4,4′-oxydibenzoic; 4,4′-sulfonyidibenzoic; and isophthalic. The preferred dicarboxylic acid residues are isophthalic, terephthalic, and 1,4-cyclohexanedicarboxylic acids, or if diesters are used, dimethyl terephthalate, dimethyl isophthalate, and dimethyl-1,4-cyclohexanedicarboxylate with the residues of isophthalic and terephthalic acid being especially preferred. Although the dicarboxylic acid methyl ester is the most preferred embodiment, it is also acceptable to include higher order alkyl esters, such as ethyl, propyl, isopropyl, butyl, and so forth. In addition, aromatic esters, particularly phenyl, also may be employed.

[0049] The sulfopolyester includes about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein the functional groups are hydroxyl, carboxyl, or a combination thereof. Additional examples of concentration ranges for the sulfomonomer residues are about 4 to about 35 mole %, about 8 to about 30 mole %, and about 8 to about 25 mole %, based on the total repeating units. The sulfomonomer may be a dicarboxylic acid or ester thereof containing a sulfonate group, a diol containing a sulfonate group, or a hydroxy acid containing a sulfonate group. The term “sulfonate” refers to a salt of a sulfonic acid having the structure “—SO₃M” wherein M is the cation of the sulfonate salt. The cation of the sulfonate salt may be a metal ion such as Li⁺, Na⁺, K⁺, Mg⁺⁺, Ca⁺⁺, Ni⁺⁺, Fe⁺⁺, and the like. Alternatively, the cation of the sulfonate salt may be non-metallic such as a nitrogenous base as described, for example, in U.S. Pat. No. 4,304,901. Nitrogen-based cations are derived from nitrogen-containing bases, which may be aliphatic, cycloaliphatic, or aromatic compounds. Examples of such nitrogen containing bases include ammonia, dimethylethanolamine, diethanolamine, triethanolamine, pyridine, morpholine, and piperidine. Because monomers containing the nitrogen-based sulfonate salts typically are not thermally stable at conditions required to make the polymers in the melt, the method of this invention for preparing sulfopolyesters containing nitrogen-based sulfonate salt groups is to disperse, dissipate, or dissolve the polymer containing the required amount of sulfonate group in the form of its alkali metal salt in water and then exchange the alkali metal cation for a nitrogen-based cation.

[0050] When a monovalent alkali metal ion is used as the cation of the sulfonate salt, the resulting sulfopolyester is completely dispersible in water with the rate of dispersion dependent on the content of sulfomonomer in the polymer, temperature of the water, surface area/thickness of the sulfopolyester, and so forth. When a divalent metal ion is used, the resulting sulfopolyesters are not readily dispersed by cold water but are more easily dispersed by hot water. Utilization of more than one counterion within a single polymer composition is possible and may offer a means to tailor or fine-tune the water-responsivity of the resulting article of manufacture. Examples sulfomonomers residues include monomer residues where the sulfonate salt group is attached to an aromatic acid nucleus, such as, for example, benzene; naphthalene; diphenyl; oxydiphenyl; sulfonyldiphenyl; and methylenediphenyl or cycloaliphatic rings, such as, for example, cyclohexyl; cyclopentyl; cyclobutyl; cycloheptyl; and cyclooctyl. Other examples of sulfomonomer residues which may be used in the present invention are the metal sulfonate salt of sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, or combinations thereof. Other examples of sulfomonomers which may be used are 5-sodiosulfoisophthalic acid and esters thereof. If the sulfomonomer residue is from 5-sodiosulfoisophthalic acid, typical sulfomonomer concentration ranges are about 4 to about 35 mole %, about 8 to about 30 mole %, and about 8 to 25 mole %, based on the total moles of acid residues.

[0051] The sulfomonomers used in the preparation of the sulfopolyesters are known compounds and may be prepared using methods well known in the art. For example, sulfomonomers in which the sulfonate group is attached to an aromatic ring may be prepared by sulfonating the aromatic compound with oleum to obtain the corresponding sulfonic acid and followed by reaction with a metal oxide or base, for example, sodium acetate, to prepare the sulfonate salt. Procedures for preparation of various sulfomonomers are described, for example, in U.S. Pat. Nos. 3,779,993; 3,018,272; and 3,528,947.

[0052] It is also possible to prepare the polyester using, for example, a sodium sulfonate salt, and ion-exchange methods to replace the sodium with a different ion, such as zinc, when the polymer is in the dispersed form. This type of ion exchange procedure is generally superior to preparing the polymer with divalent salts insofar as the sodium salts are usually more soluble in the polymer reactant melt-phase.

[0053] The sulfopolyester includes one or more diol residues which may include aliphatic, cycloaliphatic, and aralkyl glycols. The cycloaliphatic diols, for example, 1,3- and 1,4-cyclohexanedimethanol, may be present as their pure cis or trans isomers or as a mixture of cis and trans isomers. As used herein, the term “diol” is synonymous with the term “glycol” and means any dihydric alcohol. Examples diols include ethylene glycol; diethylene glycol; triethylene glycol; polyethylene glycols; propylene glycol; 1,3-propanediol; 2,4-dimethyl-2-ethylhexane-1,3-diol; 2,2-dimethyl-1,3-propanediol; 2-ethyl-2-butyl-1,3-propanediol; 2-ethyl-2-isobutyl-1,3-propanediol; 1,3-butanediol; 1,4-butanediol; 1,5-pentanediol; 1,6-hexanediol; 2,2,4-trimethyl-1,6-hexanediol; thiodiethanol; 1,2-cyclohexanedimethanol; 1,3-cyclohexanedimethanol; 1,4-cyclohexanedimethanol; 2,2,4,4-tetramethyl-1,3-cyclobutanediol; p-xylylenediol, or combinations of one or more of these glycols.

[0054] The diol residues may include from about 25 mole % to about 100 mole %, based on the total diol residues, of residue of a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0055] wherein n is an integer in the range of 2 to about 500. Non-limiting examples of lower molecular weight polyethylene glycols, e.g., wherein n is from 2 to 6, are diethylene glycol, triethylene glycol, and tetraethylene glycol. Of these lower molecular weight glycols, diethylene and triethylene glycol are most preferred. Higher molecular weight polyethylene glycols (abbreviated herein as “PEG”), wherein n is from 7 to about 500, include the commercially available products known under the designation CARBOWAX®, a product of Dow Chemical Company (formerly Union Carbide). Typically, PEG's are used in combination with other diols such as, for example, diethylene glycol or ethylene glycol. Based on the values of n, which range from greater than 6 to 500, the molecular weight may range from greater than 300 to about 22,000 g/mol. The molecular weight and the mole % arc inversely proportional to each other; specifically, as the molecular weight is increased, the mole % will be decreased in order to achieve a designated degree of hydrophilicity. For example, it is illustrative of this concept to consider that a PEG having a molecular weight of 1000 may constitute up to 10 mole % of the total diol, while a PEG having a molecular weight of 10,000 would typically be incorporated at a level of less than 1 mole % of the total diol.

[0056] Certain dimer, trimer, and tetramer diols may be formed in situ due to side reactions that may be controlled by varying the process conditions. For example, varying amounts of diethylene, triethylene, and tetraethylene glycols may be formed from ethylene glycol from an acid-catalyzed dehydration reaction which occurs readily when the polycondensation reaction is carried out under acidic conditions. The presence of buffer solutions, well-known to those skilled in the art, may be added to the reaction mixture to retard these side reactions. Additional compositional latitude is possible, however, if the buffer is omitted and the dimerization, trimerization, and tetramerization reactions are allowed to proceed.

[0057] The sulfopolyester of the present invention may include from 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof. Non-limiting examples of branching monomers are 1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin, pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol, trimellitic anhydride, pyromellitic dianhydride, dimethylol propionic acid, or combinations thereof. Further examples of branching monomer concentration ranges are from 0 to about 20 mole % and from 0 to about 10 mole %. The presence of a branching monomer may result in a number of possible benefits to the sulfopolyester of the present invention, including but not limited to, the ability to tailor rheological, solubility, and tensile properties. For example, at a constant molecular weight, a branched sulfopolyester, compared to a linear analog, will also have a greater concentration of end groups that may facilitate post-polymerization crosslinking reactions. At high concentrations of branching agent, however, the sulfopolyester may be prone to gelation.

[0058] The sulfopolyester used for the fiber of the present invention has a glass transition temperature, abbreviated herein as “Tg”, of at least 25° C. as measured on the dry polymer using standard techniques, such as differentical scanning calorimetry (“DSC”), well known to persons skilled in the art. The Tg measurements of the sulfopolyesters of the present invention are conducted using a “dry polymer”, that is, a polymer sample in which adventitious or absorbed water is driven off by heating to polymer to a temperature of about 200° C. and allowing the sample to return to room temperature. Typically, the sulfopolyester is dried in the DSC apparatus by conducting a first thermal scan in which the sample is heated to a temperature above the water vaporization temperature, holding the sample at that temperature until the vaporization of the water absorbed in the polymer is complete (as indicated by an a large, broad endotherm), cooling the sample to room temperature, and then conducting a second thermal scan to obtain the Tg measurement. Further examples of glass transition temperatures exhibited by the sulfopolyester are at least 30° C., at least 40° C., at least 50° C., and at least 60° C. Although other Tg's are possible, typical glass transition temperatures of the dry sulfopolyesters our invention are 35° C., 48° C., 55° C., and 65° C.

[0059] Our novel fibers may consist essentially of or, consist of, the sulfopolyesters described hereinabove. In another embodiment, however, the sulfopolyesters of this invention may be a single polyester or may be blended with one or more supplemental polymers to modify the properties of the resulting fiber. The supplemental polymer may or may not be water-dispersible depending on the application and may be miscible or immiscible with the sulfopolyester. If the supplemental polymer is water-nondispersible, it is preferred that the blend with the sulfopolyester is immiscible. The term “miscible”, as used herein, is intended to mean that the blend has a single, homogeneous amorphous phase as indicated by a single composition-dependent Tg. For example, a first polymer that is miscible with second polymer may be used to “plasticize” the second polymer as illustrated, for example, in U.S. Pat. No. 6,211,309. By contrast, the term “immiscible”, as used herein, denotes a blend that shows at least 2, randomly mixed, phases and exhibits more than one Tg. Some polymers may be immiscible and yet compatible with the sulfopolyester. A further general description of miscible and immiscible polymer blends and the various analytical techniques for their characterization may be found in Polymer Blends Volumes 1 and 2, Edited by D. R. Paul and C. B. Bucknall, 2000, John Wiley & Sons, Inc.

[0060] Non-limiting examples of water-dispersible polymers that may be blended with the sulfopolyester are polymethacrylic acid, polyvinyl pyrrolidone, polyethylene-acrylic acid copolymers, polyvinyl methyl ether, polyvinyl alcohol, polyethylene oxide, hydroxy propyl cellulose, hydroxypropyl methyl cellulose, methyl cellulose, ethyl hydroxyethyl cellulose, isopropyl cellulose, methyl ether starch, polyacrylamides, poly(N-vinyl caprolactam), polyethyl oxazoline, poly(2-isopropyl-2-oxazoline), polyvinyl methyl oxazolidone, water-dispersible sulfopolyesters, polyvinyl methyl oxazolidimone, poly(2,4-dimethyl-6-triazinylethylene), and ethylene oxide-propylene oxide copolymers. Examples of polymers which are water-nondispersible that may be blended with the sulfopolyester include, but are not limited to, polyolefins, such as homo- and copolymers of polyethylene and poly-propylene; poly(ethylene terephthalate); poly(butylene terephthalate); and polyamides, such as nylon-6; polylactides; caprolactone; Eastar Bio® (poly(tetramethylene adipate-co-terephthalate), a product of Eastman Chemical Company); polycarbonate; polyurethane; and polyvinyl chloride.

[0061] According to our invention, blends of more than one sulfopolyester may be used to tailor the end-use properties of the resulting fiber or fibrous article, for example, a nonwoven fabric or web. Thus, blending may also be exploited to alter the processing characteristics of a sulfopolyester to facilitate the fabrication of a nonwoven. In another example, an immiscible blend of polypropylene and sulfopolyester may provide a conventional nonwoven web that will break apart and completely disperse in water as true solubility is not needed. In this latter example, the desired performance is related to maintaining the physical properties of the polypropylene while the sulfopolyester is only a spectator during the actual use of the product or, alternatively, the sulfopolyester is fugitive and is removed before the final form of the product is utilized.

[0062] The sulfopolyester and supplemental polymer may be blended in batch, semicontinuous, or continuous processes. Small scale batches may be readily prepared in any high-intensity mixing devices well-known to those skilled in the art, such as Banbury mixers, prior to melt-spinning fibers. The components may also be blended in solution in an appropriate solvent. The melt blending method includes blending the sulfopolyester and supplemental polymer at a temperature sufficient to melt the polymers. The blend may be cooled and pelletized for further use or the melt blend can be melt spun directly from this molten blend into fiber form. The term “melt” as used herein includes, but is not limited to, merely softening the polyester. For melt mixing methods generally known in the polymers art, see “Mixing and Compounding of Polymers” (I. Manas-Zloczower & Z. Tadmor editors, Carl Hanser Verlag Publisher, 1994, New York, N.Y.).

[0063] Our invention also provides a water-dispersible fiber comprising a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., wherein the sulfpolyester comprises: (i) about 50 to about 96 mole % of a residue of isophthalic acid, based on the total acid residues; (ii) about 4 to about 30 mole %, based on the total acid residues, of a residue of sodiosulfoisophthalic acid; (iii) one or more diol residues wherein at least 25 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0064] wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof. As described hereinabove, the fiber may optionally include a first water-dispersible polymer blended with the sulfopolyester; and, optionally, a water-nondispersible polymer blended with the sulfopolyester such that the blend is an immiscible blend. The first water-dispersible polymer is as described hereinabove. The sulfopolyester should have a glass transition temperature (Tg) of at least 25° C., but may have, for example, a Tg of about 35° C., about 48° C., about 55° C., and about 65° C. The sulfopolyester may contain other concentrations of isophthalic acid residues, for example, about 60 to about 95 mole %, and about 75 to about 95 mole %. Further examples of isophthalic acid residue concentrations ranges are about 70 to about 85 mole %, about 85 to about 95 mole % and about 90 to about 95 mole %. The sulfopolyester also may comprise about 25 to about 95 mole % of the residues of diethylene glycol. Further examples of diethylene glycol residue concentration ranges include about 50 to about 95 mole %, about 70 to about 95 mole %, and about 75 to about 95 mole %. The sulfopolyester also may include the residues of ethylene glycol and/or 1,4-cyclohexanedimethanol, abbreviated herein as “CHDM”. Typical concentration ranges of CHDM residues are about 10 to about 75 mole %, about 25 to about 65 mole %, and about 40 to about 60 mole %. Typical concentration ranges of ethylene glycol residues are are about 10 to about 75 mole %, about 25 to about 65 mole %, and about 40 to about 60 mole %. In another embodiment, the sulfopolyester comprises is about 75 to about 96 mole % of the residues of isophthalic acid and about 25 to about 95 mole % of the residues of diethylene glycol.

[0065] The sulfopolyesters of the instant invention are readily prepared from the appropriate dicarboxylic acids, esters, anhydrides, or salts, sulfomonomer, and the appropriate diol or diol mixtures using typical polycondensation reaction conditions. They may be made by continuous, semi-continuous, and batch modes of operation and may utilize a variety of reactor types. Examples of suitable reactor types include, but are not limited to, stirred tank, continuous stirred tank, slurry, tubular, wiped-film, falling film, or extrusion reactors. The term “continuous” as used herein means a process wherein reactants are introduced and products withdrawn simultaneously in an uninterrupted manner. By “continuous” it is meant that the process is substantially or completely continuous in operation and is to be contrasted with a “batch” process. “Continuous” is not meant in any way to prohibit normal interruptions in the continuity of the process due to, for example, start-up, reactor maintenance, or scheduled shut down periods. The term “batch” process as used herein means a process wherein all the reactants are added to the reactor and then processed according to a predetermined course of reaction during which no material is fed or removed into the reactor. The term “semicontinuous” means a process where some of the reactants are charged at the beginning of the process and the remaining reactants are fed continuously as the reaction progresses. Alternatively, a semicontinuous process may also include a process similar to a batch process in which all the reactants are added at the beginning of the process except that one or more of the products are removed continuously as the reaction progresses. The process is operated advantageously as a continuous process for economic reasons and to produce superior coloration of the polymer as the sulfopolyester may deteriorate in appearance if allowed to reside in a reactor at an elevated temperature for too long a duration.

[0066] The sulfopolyesters of the present invention are prepared by procedures known to persons skilled in the art. The sulfomonomer is most often added directly to the reaction mixture from which the polymer is made, although other processes are known and may also be employed, for example, as described in U.S. Pat. Nos. 3,018,272, 3,075,952, and 3,033,822. The reaction of the sulfomonomer, diol component and the dicarboxylic acid component may be carried out using conventional polyester polymerization conditions. For example, when preparing the sulfopolyesters by means of an ester interchange reaction, i.e., from the ester form of the dicarboxylic acid components, the reaction process may comprise two steps. In the first step, the diol component and the dicarboxylic acid component, such as, for example, dimethyl isophthalate, are reacted at elevated temperatures, typically, about 150° C. to about 250° C. for about 0.5 to about 8 hours at pressures ranging from about 0.0 kPa gauge to about 414 kPa gauge (60 pounds per square inch, “psig”). Preferably, the temperature for the ester interchange reaction ranges from about 180° C. to about 230° C. for about 1 to about 4 hours while the preferred pressure ranges from about 103 kPa gauge (15 psig) to about 276 kPa gauge (40 psig). Thereafter, the reaction product is heated under higher temperatures and under reduced pressure to form sulfopolyester with the elimination of diol, which is readily volatilized under these conditions and removed from the system. This second step, or polycondensation step, is continued under higher vacuum and a temperature which generally ranges from about 230° C. to about 350° C., preferably about 250° C. to about 31° C. and most preferably about 260° C. to about 290° C. for about 0.1 to about 6 hours, or preferably, for about 0.2 to about 2 hours, until a polymer having the desired degree of polymerization, as determined by inherent viscosity, is obtained. The polycondensation step may be conducted under reduced pressure which ranges from about 53 kPa (400 torr) to about 0.013 kPa (0.1 torr). Stirring or appropriate conditions are used in both stages to ensure adequate heat transfer and surface renewal of the reaction mixture. The reactions of both stages are facilitated by appropriate catalysts such as, for example, alkoxy titanium compounds, alkali metal hydroxides and alcoholates, salts of organic carboxylic acids, alkyl tin compounds, metal oxides, and the like. A three-stage manufacturing procedure, similar to that described in U.S. Pat. No. 5,290,631, may also be used, particularly when a mixed monomer feed of acids and esters is employed.

[0067] To ensure that the reaction of the diol component and dicarboxylic acid component by an ester interchange reaction mechanism is driven to completion, it is preferred to employ about 1.05 to about 2.5 moles of diol component to one mole dicarboxylic acid component. Persons of skill in the art will understand, however, that the ratio of diol component to dicarboxylic acid component is generally determined by the design of the reactor in which the reaction process occurs.

[0068] In the preparation of sulfopolyester by direct esterification, i.e., from the acid form of the dicarboxylic acid component, sulfopolyesters are produced by reacting the dicarboxylic acid or a mixture of dicarboxylic acids with the diol component or a mixture of diol components. The reaction is conducted at a pressure of from about 7 kPa gauge (1 psig) to about 1379 kPa gauge (200 psig), preferably less than 689 kPa (100 psig) to produce a low molecular weight, linear or branched sulfopolyester product having an average degree of polymerization of from about 1.4 to about 10. The temperatures employed during the direct esterification reaction typically range from about 180° C. to about 280° C., more preferably ranging from about 220° C. to about 270° C. This low molecular weight polymer may then be polymerized by a polycondensation reaction.

[0069] The fiber of this invention also may contain other conventional additives and ingredients which do not deleteriously affect their end use. For example, additives such as fillers, surface friction modifiers, light and heat stabilizers, extrusion aids, antistatic agents, colorants, dyes, pigments, fluorescent brighteners, antimicrobials, anticounterfeiting markers, hydrophobic and hydrophilic enhancers, viscosity modifiers, slip agents, tougheners, adhesion promoters, and the like may be used. Colorants, sometimes referred to as toners, may be added to impart a desired neutral hue and/or brightness to the sulfopolyester. When colored fibers are desired, pigments or colorants may be included in the sulfopolyester reaction mixture during the reaction of the diol monomer and the dicarboxylic acid monomer or they may be melt blended with the preformed sulfopolyester. A preferred method of including colorants is to use a colorant having thermally stable organic colored compounds having reactive groups such that the colorant is copolymerized and incorporated into the sulfopolyester to improve its hue. For example, colorants such as dyes possessing reactive hydroxyl and/or carboxyl groups, including, but not limited to, blue and red substituted anthraquinones, may be copolymerized into the polymer chain. When dyes are employed as colorants, they may be added to the copolyester reaction process after an ester interchange or direct esterification reaction.

[0070] For the purposes of this invention, the term “fiber” refers to a polymeric body of high aspect ratio capable of being formed into two or three dimensional articles such as woven or nonwoven fabrics. In the context of the present invention, the term “fiber” is synonymous with “fibers” and intented to mean one or more fibers. The fiber may be a staple, monofilament or multifilament fiber that has a shaped or round cross-section. Most fiber forms are heatset. The fiber may include the various antioxidants, pigments, and additives as described herein.

[0071] Monofilament fibers generally range in size from about 15 to about 8000 denier per filament (abbreviated herein as “d/f”). Our novel fibers typically will have d/f values in the range of about 40 to about 5000. Monofilaments may be in the form of unicomponent or bicomponent fibers. The multifilament fibers of our invention will preferably range in size from about 1.5 micrometers for melt blown webs, about 0.5 to about 50 d/f for staple fibers, and up to about 5000 d/f for monofilament fibers. Multifilament fibers may also be used as crimped or uncrimped yarns and tows. Fibers used in melt blown web and melt spun fabrics may be produced in microdenier sizes.

[0072] Although the water-dispersible fibers of the present invention are unicomponent fibers, the sulfopolyesters used in their preparation also are advantageous for the preparation of bicomponent and multicomponent fibers. For example, the sulfopolyester and a supplemental water-nondispersible polymer may be used to prepare a bicomponent fiber having an engineered geometry such as, for example, a side-by-side, “islands-in-the-sea”, sheath/core, segmented pie, or other configurations known to persons skilled in the art. Other multicomponent configurations are also possible. Subsequent removal of a side, the “sea”, or a portion of the “pie” can result in very fine fibers. The process of preparing bicomponent fibers also is well known to persons skilled in the art. In a bicomponent fiber, the sulfopolyester fibers of this invention may be present in amounts of about 10 to about 90 weight % and will generally be used in the sheath portion of sheath/core fibers. The other component may be from a wide range of other polymeric materials such as, for example, poly(ethylene) terephthalate, poly(butylene) terephthalate, poly(trimethylene) terephthalate, polylactides and the like as well as polyolefins, cellulose esters, and polyamides. Typically, when a water-insoluble or water-nondispersible supplemental polymer is used, the resulting bicomponent or multicomponent fiber is not completely water-dispersible. Side by side combinations with significant differences in thermal shrinkage can be utilized for the development of a spiral crimp. If crimping is desired, a saw tooth or stuffer box crimp is generally suitable for many applications. If the second polymer component is in the core of a sheath/core configuration, such a core optionally may be stabilized.

[0073] The sulfopolyesters are particularly useful for “islands-in-the-sea” configurations as they only require soft water to disperse, as compared to the caustic-containing solutions that are sometimes required to remove other known “sea” polymers in islands-in-the-sea bicomponent fiber configurations. The sulfopolyester may be later removed by dissolving the interfacial layers or pie segments and leaving the smaller filaments or microfibers of the non-soluble component. Other applications where the properties of both polymers are desired may require that a miscible blend be employed.

[0074] Typical applications of these remaining microfibers include artificial leathers, suedes, wipes, and filter media. The ionic nature of sulfopolyesters also results in advantageously poor “solubility” in saline media, such as body fluids. Such properties are desirable in personal care products and cleaning wipes that are flushable or otherwise disposed in sanitary sewage systems. Selected sulfopolyesters have also been utilized as dispersing agents in dye baths and soil redeposition preventative agents during laundry cycles.

[0075] The instant invention also includes a fibrous article comprising the water-dispersible fiber described hereinabove. The term “fibrous article” is understood to mean any article having or resembling fibers. Non-limiting examples of fibrous articles include multifilament fibers, yarns, cords, tapes, fabrics, melt blown webs, nonwoven webs and fabrics, and combinations thereof; items having one or more layers of fibers, such as, for example, multilayer nonwovens, laminates, and composites from such fibers, gauzes, bandages, diapers, training pants, tampons, surgical gowns and masks, feminine napkins; and the like. Further, the fibrous articles may include replacement inserts for various personal hygiene and cleaning products. The fibrous article of the present invention may be bonded, laminated, attached to, or used in conjunction with other materials which may or may not be water-dispersible. The fibrous article, for example, a nonwoven fabric layer, may be bonded to a flexible plastic film or backing of a water-nondispersible material, such as polyethylene. Such an assembly, for example, could be used as one component of a disposable diaper. In addition, the fibrous article may result from overblowing fibers onto another substrate to form highly assorted combinations of engineered melt blown, spunbond, film, or membrane structures.

[0076] The fibrous articles of the instant invention include nonwoven fabrics and webs. A nonwoven fabric is defined as a fabric made directly from fibrous webs without weaving or knitting operations. The nonwoven assembly is held together by 1) mechanical fiber cohesion and interlocking in a web or mat; 2) various techniques of fusing of fibers utilizing the thermoplastic properties of certain polymers and polymer blends; 3) use of a binding resin such as starch, casein, a cellulose derivative, or a synthetic resin, such as an acrylic latex or urethane; 4) powder adhesive binders; or 5) combinations thereof. The fibers are often deposited in a random manner, although orientation in one direction is possible, followed by bonding using one of the methods described above.

[0077] The fibrous articles of our invention further also may comprise one or more layers of water-dispersible fibers. The fiber layers may be one or more nonwoven fabric layers, a layer of loosely bound overlapping fibers, or a combination thereof. In addition, the fibrous articles may include personal and health care products such as, but not limited to, child care products, such as infant diapers; child training pants; adult care products, such as adult diapers and adult incontinence pads; feminine care products, such as feminine napkins, panty liners, and tampons; wipes; fiber-containing cleaning products; medical and surgical care products, such as medical wipes, tissues, gauzes, examination bed coverings, surgical masks, gowns, bandages, and wound dressings; fabrics; elastomeric yarns, wipes, tapes, other protective barriers, and packaging material. The fibrous articles may be used to absorb liquids or may be pre-moistened with various liquid compositions and used to deliver these compositions to a surface. Non-limiting examples of liquid compositions include detergents; wetting agents; cleaning agents; skin care products, such as cosmetics, ointments, medications, emollients, and fragrances. The fibrous articles also may include various powders and particulates to improve absorbency or as delivery vehicles. Examples of powders and particulates include, but are not limited to, talc, starches, various water absorbent, water-dispersible, or water swellable polymers, such as super absorbent polymers, sulfopolyesters, and poly(vinylalcohols), silica, pigments, and microcapsules. Additives may also be present, but are not required, as needed for specific applications. Examples of additives include, but are not limited to, oxidative stabilizers, UV absorbers, colorants, pigments, opacifiers (delustrants), optical brighteners, fillers, nucleating agents, plasticizers, viscosity modifiers, surface modifiers, antimicrobials, disinfectants, cold flow inhibitors, branching agents, and catalysts.

[0078] In addition to being water-dispersible, the fibrous articles described above may be flushable. The term “flushable” as used herein means capable of being flushed in a conventional toilet, and being introduced into a municipal sewage or residential septic system, without causing an obstruction or blockage in the toilet or sewage system.

[0079] The fibrous article may further comprise a water-dispersible film comprising a second water-dispersible polymer. The second water-dispersible polymer may be the same as or different from the previously described water-dispersible polymers used in the fibers and fibrous articles of the present invention. In one embodiment, for example, the second water-dispersible polymer may be an additional sulfopolyester which, in turn, comprises: (i) about 50 to about 96 mole % of a residue of isophthalic acid, based on the total acid residues; (ii) about 4 to about 30 mole %, based on the total acid residues, of a residue of sodiosulfoisophthalic acid; (iii) one or more diol residues wherein at least 15 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0080] wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof. The additional sulfopolyester may be blended with one or more supplemental polymers, as described hereinabove, to modify the properties of the resulting fibrous article. The supplemental polymer may or may not be water-dispersible depending on the application. The supplemental polymer may be miscible or immiscible with the additional sulfopolyester.

[0081] The additional sulfopolyester may contain other concentrations of isophthalic acid residues, for example, about 60 to about 95 mole %, and about 75 to about 95 mole %. Further examples of isophthalic acid residue concentrations ranges are about 70 to about 85 mole %, about 85 to about 95 mole % and about 90 to about 95 mole %. The additional sulfopolyester also may comprise about 25 to about 95 mole % of the residues of diethylene glycol. Further examples of diethylene glycol residue concentration ranges include about 50 to about 95 mole %, about 70 to about 95 mole %, and about 75 to about 95 mole %. The additional sulfopolyester also may include the residues of ethylene glycol and/or 1,4-cyclohexanedimethanol. Typical concentration ranges of CHDM residues are about 10 to about 75 mole %, about 25 to about 65 mole %, and about 40 to about 60 mole %. Typical concentration ranges of ethylene glycol residues are are about 10 to about 75 mole %, about 25 to about 65 mole %, and about 40 to about 60 mole %. In another embodiment, the additional sulfopolyester comprises is about 75 to about 96 mole % of the residues of isophthalic acid and about 25 to about 95 mole % of the residues of diethylene glycol.

[0082] According to the invention, the sulfopolyester film component of the fibrous article may be produced as a monolayer or multilayer film. The monolayer film may be produced by conventional casting techniques. The multilayered films may be produced by conventional lamination methods or the like. The film may be of any convenient thickness, but total thickness will normally be between about 2 and about 50 mil.

[0083] The film-containing fibrous articles may include one or more layers of water-dispersible fibers as described above. The fiber layers may be one or more nonwoven fabric layers, a layer of loosely bound overlapping fibers, or a combination thereof. In addition, the film-containing fibrous articles may include personal and health care products as described hereinabove.

[0084] As described previously, the fibrous articles also may include various powders and particulates to improve absorbency or as delivery vehicles. Thus, in one embodiment, our fibrous article comprises a powder comprising a third water-dispersible polymer that may be the same as or different from the water-dispersible polymer components described previously herein. Other examples of powders and particulates include, but are not limited to, talc, starches, various water absorbent, water-dispersible, or water swellable polymers, such as poly(acrylonitiles), sulfopolyesters, and poly(vinyl alcohols), silica, pigments, and microcapsules.

[0085] Our novel fiber and fibrous articles have many possible uses in addition to the applications described above. One novel application involves the melt blowing a film or nonwoven fabric onto flat, curved, or shaped surfaces to provide a protective layer. One such layer might provide surface protection to durable equipment during shipping. At the destination, before putting the equipment into service, the outer layers of sulfopolyester could be washed off. A further embodiment of this general application concept could involve articles of personal protection to provide temporary barrier layers for some reusable or limited use garments or coverings. For the military, activated carbon and chemical absorbers could be sprayed onto the attenuating filament pattern just prior to the collector to allow the melt blown matrix to anchor these entities on the exposed surface. The chemical absorbers can even be changed in the forward operations area as the threat evolves by melt blowing on another layer.

[0086] A major advantage inherent to sulfopolyesters is the facile ability to remove or recover the polymer from aqueous dispersions via flocculation or precipitation by adding ionic moieties (i.e., salts). Other methods, such as pH adjustment, adding nonsolvents, freezing, and so forth may also be employed. Therefore, fibrous articles, such as outer wear protective garments, after successful protective barrier use and even if the polymer is rendered as hazardous waste, can potentially be handled safely at much lower volumes for disposal using accepted protocols, such as incineration.

[0087] Undissolved or dried sulfopolyesters are known to form strong adhesive bonds to a wide array of substrates, including, but not limited to fluff pulp, cotton, acrylics, rayon, lyocell, PLA (polylactides), cellulose acetate, poly(ethylene) terephthalate, poly(butylene) terephthalate, poly(trimethylene) terephthalate, poly(cyclohexylene) terephthalate, copolyesters, polyamides (nylons), stainless steel, aluminum, treated polyolefins, PAN (polyacrylonitriles), and polycarbonates. Thus, our nonwoven fabrics may be used as laminating adhesives or binders that may be bonded by known techniques, such as thermal, radio frequency (RF), microwave, and ultrasonic methods. Adaptation of sulfopolyesters to enable RF activation is disclosed in a number of recent patents. Thus, our novel nonwoven fabrics may have dual or even multifunctionality in addition to adhesive properties. For example, a disposable baby diaper could be obtained where a nonwoven of the present invention serves as both an water-responsive adhesive as well as a fluid managing component of the final assembly.

[0088] Our invention also provides a process for water-dispersible fibers comprising (I) providing a water-dispersible polymer composition comprising a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., wherein the sulfopolyester comprises: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more metal sulfonate groups attached to an aromatic or cycloaliphatic ring wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; and (iii) one or more diol residues wherein at least 20 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0089] wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein the functional groups are hydroxyl, carboxyl, or a combination thereof; (II) heating the polymer composition to a temperature above its flow point; and (III) melt spinning filaments. As described hereinabove, a water-dispersible polymer, optionally, may be blended with the sulfopolyester. In addition, a water-nondispersible polymer, optionally, may be blended with the sulfopolyester to form a blend such that blend is an immiscible blend. The term “flow point”, as used herein, means the temperature at which the viscosity of the polymer composition permits extrusion or other forms of processing through a spinnerette or extrusion die. The dicarboxylic acid residue may comprise from about 60 to about 100 mole % of the acid residues depending on the type and concentration of the sulfomonomer. Other examples of concentration ranges of dicarboxylic acid residues are from about 60 mole % to about 95 mole % and about 70 mole % to about 95 mole %. The preferred dicarboxylic acid residues are isophthalic, terephthalic, and 1,4-cyclohexane-dicarboxylic acids or if diesters are used, dimethyl terephthalate, dimethyl isophthalate, and dimethyl-1,4-cyclohexanedicarboxylate with the residues of isophthalic and terephthalic acid being especially preferred.

[0090] The sulfomonomer may be a dicarboxylic acid or ester thereof containing a sulfonate group, a diol containing a sulfonate group, or a hydroxy acid containing a sulfonate group. Additional examples of concentration ranges for the sulfomonomer residues are about 4 to about 25 mole %, about 4 to about 20 mole %, about 4 to about 15 mole %, and about 4 to about 10 mole %, based on the total repeating units. The cation of the sulfonate salt may be a metal ion such as Li⁺, Na⁺, K⁺, Mg⁺⁺, Ca₊₊, Ni₊₊, Fe₊₊, and the like. Alternatively, the cation of the sulfonate salt may be non-metallic such as a nitrogenous base as described previously. Examples examples of sulfomonomer residues which may be used in the process of the present invention are the metal sulfonate salt of sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, or combinations thereof. Another example of sulfomonomer which may be used is 5-sodiosulfoisophthalic acid or esters thereof. If the sulfomonomer residue is from 5-sodiosulfoisophthalic acid, typical sulfomonomer concentration ranges are about 4 to about 35 mole %, about 8 to about 30 mole %, and about 10 to 25 mole %, based on the total acid residues.

[0091] The sulfopolyester of our includes one or more diol residues which may include aliphatic, cycloaliphatic, and aralkyl glycols. The cycloaliphatic diols, for example, 1,3- and 1,4-cyclohexanedimethanol, may be present as their pure cis or trans isomers or as a mixture of cis and trans isomers. Non-limiting examples of lower molecular weight polyethylene glycols, e.g., wherein n is from 2 to 6, are diethylene glycol, triethylene glycol, and tetraethylene glycol. Of these lower molecular weight glycols, diethylene and triethylene glycol are most preferred. The sulfopolyester may optionally include a branching monomer. Examples of branching monomers are as described hereinabove. Further examples of branching monomer concentration ranges are from 0 to about 20 mole % and from 0 to about 10 mole %. The sulfpolyester of our novel process has a Tg of at least 25° C. Further examples of glass transition temperatures exhibited by the sulfopolyester may be at least 30° C., at least 40° C., at least 50° C., and at least 60° C. Typical glass transition temperatures of the sulfopolyesters of the fibers our invention are 35° C., 48° C., 55° C., and 65° C.

[0092] The water-dispersible fibers are prepared by a melt blowing process. The polymer is melted in an extruder and forced through a die. The extrudate exiting the die is rapidly attenuated to ultrafine diameters by hot, high velocity air. The orientation, rate of cooling, glass transition temperature (Tg), and rate of crystallization of the fiber are important because they affect the viscosity and processing properties of the polymer during attenuation. The filament is collected on a renewable surface, such as a moving belt, cylindrical drum, rotating mandrel, and so forth. Predrying of pellets (if needed), extruder zone temperature, melt temperature, screw design, throughput rate, air temperature, air flow (velocity), die air gap and set back, nose tip hole size, die temperature, die-to-collector (DCP) distance, quenching environment, collector speed, and post treatments are all factors that influence product characteristics such as filament diameters, basis weight, web thickness, pore size, softness, and shrinkage. The high velocity air also may be used to move the filaments in a somewhat random fashion that results in extensive interlacing. If a moving belt is passed under the die, a nonwoven fabric can be produced by a combination of over-lapping laydown, mechanical cohesiveness, and thermal bonding of the filaments. Overblowing onto another substrate, such as a spunbond or backing layer, is also possible. If the filaments are taken up on an rotating mandrel, a cylindrical product is formed.

[0093] The instant invention, therefore, further provides a process for water-dispersible, nonwoven fabric comprising (A) providing a water-dispersible polymer composition comprising a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., wherein the sulfopolyester comprises: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more metal sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (iii) one or more diol residues wherein at least 20 mole %, based on the total hydroxyl residues, is a poly(ethylene glycol) having a structure

H—(OCH₂—CH₂)_(n)—OH

[0094] wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; wherein the sulfopolyester has a glass transistion temperature (Tg) of at least 25° C.; (B) heating the water-dispersible polymer composition to a temperature above its flow point; (C) melt-spinning filaments; and (D) overlapping and collecting said filaments of Step C to form a nonwoven fabric. As described hereinabove, a water-dispersible polymer, optionally, may be blended with the sulfopolyester. In addition, a water-nondispersible polymer, optionally, may be blended with the sulfopolyester to form a blend such that blend is an immiscible blend. The dicarboxylic acid, sulfomonomer, and branching monomer residues are as described previously. The sulfpolyester has a Tg of at least 25° C. Further examples of glass transition temperatures exhibited by the sulfopolyester may be at least 30° C., at least 40° C., at least 50° C., and at least 60° C. Typical glass transition temperatures of the sulfopolyesters of the fibrous articles our invention are 35° C., 48° C., 55° C., and 65° C.

[0095] The invention is further illustrated by the following examples.

EXAMPLES

[0096] All pellet samples were predried under vacuum at room temperature for at least 12 hours. The dispersion times shown in Table 3 are for either complete dispersion or dissolution of the nonwoven fabric samples. The abbreviation “CE”, used in Tables 2 and 3 mean “comparative example”.

Example 1

[0097] A sulfopolyester containing 76 mole %, isophthalic acid, 24 mole % of sodiosulfoisophthalic acid, 76 mole % diethylene glycol, and 24 mole % 1,4-cyclohexanedimethanol with an Ih.V. of 0.29 and a Tg of 48° C. was meltblown through a nominal 6-inch die (30 holes/inch in the nosepiece) onto a cylindrical collector using the conditions shown in Table 1. Interleafing paper was not required. A soft, handleable, flexible web was obtained that did not block during the roll winding operation. Physical properties are provided in Table 2. A small piece (1″×3″) of the nonwoven fabric was easily dispersed in both room temperature (RT) and 50° C. water with slight agitation as shown by data in Table 3. TABLE 1 Melt Blowing Conditions Operating Condition Typical Value Die Configuration Die tip hole diameter 0.0185 inches Number of holes 120 Air gap 0.060 inches Set back 0.060 inches Extruder Barrel Temperatures (° F.) Zone 1 350 Zone 2 510 Zone 3 510 Die Temperatures (° F.) Zone 4 510 Zone 5 510 Zone 6 510 Zone 7 510 Zone 8 510 Air Temperatures (° F.) Furnace exit 1 350 Furnace exit 2 700 Furnace exit 3 700 Die 530-546 Extrusion Conditions Air pressure 3.0 psi Melt pressure after pump 99-113 psi Take Up Conditions Throughput 0.3 g/hole/min 0.5 g/hole/min Basis weight 36 g/m² Collector speed 20 ft/min Collector distance 12 inches

[0098] TABLE 2 Physical Properties of Nonwovens Tg/Tm (° C.) Filament Diameter (μm) IhV (sulfopoly./ Example Minimum Maximum Average (before/after) PP) 1 5 18 8.7 0.29/0.26 39/not applicable 2 3 11 7.7 0.40/0.34 36/not applicable CE 1 2 20 8 Not 36/163 measured CE 2 4 10 7 Not 36/164 measured CE 3 4 11 6 Not 35/161 measured

[0099] TABLE 3 Dispersbility of Nonwovens Water Tem- Initial Significant Complete Exam- perature Disintegration Disintegration Dispersion ple (° C.) (minutes) (minutes) (minutes) 1 23 <0.25 1 2 50 <0.17 0.5 1 2 23 8 14 19  50 <0.5 5 8 80 <0.5 2 5 CE 1 23 0.5 >15 No dispersion of PP 50 0.5 >15 No dispersion of PP CE 2 23 0.5 >15 No dispersion of PP 50 0.5 >15 No dispersion of PP CE 3 23 <0.5 6 No dispersion of PP 50 <0.5 4 No dispersion of PP

Example 2

[0100] A sulfopolyester containing 89 mole %, isophthalic acid, 11 mole % of sodiosulfoisophthalic acid, 72 mole % diethylene glycol, and 28 mole % ethylene glycol with an Ih.V. of 0.4 and a Tg of 35° C. was meltblown through a 6-inch die using conditions similar to those in Table 1. A soft handleable, flexible web was obtained that did not block during a roll winding operation. Physical properties are provided in Table 2. A small piece (1″×2″) of the nonwoven fabric was easily and completely dispersed at 50° C. and 80° C.; at RT (23° C.), the fabric required a longer period of time for complete dispersion as shown by the data in Table 3.

[0101] It was found that the compositions in Examples 1 and 2 can be overblown onto other nonwoven substrates. It is also possible to condense and wrap shaped or contoured forms that are used instead of conventional web collectors. Thus, it is possible to obtain circular “roving” or plug forms of the webs.

Comparative Examples 1-3

[0102] Pellets of a sulfopolyester containing 89 mole %, isophthalic acid, 11 mole % of sodiosulfoisophthalic acid, 72 mole % diethylene glycol, and 28 mole % ethylene glycol with an Ih.V. of 0.4 and a Tg of 35° C. were combined with polypropylene (Basell PF 008) pellets in bicomponent ratios (by wt %) of:

[0103] 75 PP: 25 sulfopolyester (Example 3)

[0104] 50 PP: 50 sulfopolyester (Example 4)

[0105] 25 PP: 75 sulfopolyester (Example 5)

[0106] The PP had a MFR (melt flow rate) of 800. A melt blowing operation was performed on a line equipped with a 24-inch wide die to yield handleable, soft, flexible, but nonblocking webs with the physical properties provided in Table 2. Small pieces (1″×4″) of nonwoven fabric readily disintegrated as reported in Table 3. None of the fibers, however, were completely water-dispersible because of the insoluble polypropylene component.

Example 3

[0107] A circular piece (4″ diameter) of the nonwoven produced in Example 2 was used as an adhesive layer between two sheets of cotton fabric. A Hannifin melt press was used to fuse the two sheets of cotton together by applying a pressure 35 psig at 200° C. for 30 seconds. The resultant assembly exhibited exceptionally strong bond strength. The cotton substrate shredded before adhesive or bond failure. Similar results have also been obtained with other cellulosics and with PET polyester substrates. Strong bonds were also produced by ultrasonic bonding techniques.

Comparative Example 4

[0108] A PP (Exxon 3356G) with a 1200 MFR was melt blown using a 24″ die to yield a flexible nonwoven fabric that did not block and was easily unwound from a roll. Small pieces (1″×4″) did not show any response (i.e., no disintegration or loss in basis weight) to water when immersed in water at RT or 50° C. for 15 minutes.

Example 4

[0109] Unicomponent fibers of a sulfopolyester containing 82 mole % isophthalic acid, 18 mole % of sodiosulfoisophthalic acid, 54 mole % diethylene glycol, and 46 mole % 1,4-cyclohexanedimethanol with a Tg of 55° C. were melt spun at melt temperatures of 245° C. (473° F.) on a lab staple spinning line. As-spun denier was approximately 8 d/f. Some blocking was encountered on the take-up tubes, but the 10-filament strand readily dissolved within 10-19 seconds in unagitated, demineralized water at 82° C. and a pH between 5 and 6.

Example 5

[0110] Unicomponent fibers obtained from a blend (75:25) of a sulfopolyester containing 82 mole % isophthalic acid, 18 mole % of sodiosulfoisophthalic acid, 54 mole % diethylene glycol, and 46 mole % 1,4-cyclohexanedimethanol (Tg of 55° C.) and a sulfopolyester containing 91 mole % isophthalic acid, 9 mole % of sodiosulfoisophthalic acid, 25 mole % diethylene glycol, and 75 mole % 1,4-cyclohexanedimethanol (Tg of 65° C.), respectively, were melt spun on a lab staple spinning line. The 10-filament strands did not show any blocking on the take-up tubes, but readily dissolved within 20-43 seconds in unagitated, demineralized water at 82° C. and a pH between 5 and 6.

Comparative Example 5

[0111] 100701 The blend described in Example 8 was co-spun with PET to yield bicomponent islands-in-the-sea fibers. A configuration was obtained where the sulfopolyester “sea” is 20 wt % of the fiber containing 80 wt % of PET “islands”. The spun yarn elongation was 190% immediately after spinning. Blocking was not encountered as the yarn was satisfactorily unwound from the bobbins and processed a week after spinning. In a subsequent operation, the “sea” was dissolved by passing the yarn through an 88° C. soft water bath leaving only fine PET filaments. 

We claim:
 1. A water-dispersible fiber comprising: A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfpolyester comprising: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (iii) one or more diol residues wherein at least 25 mole %, based on the total hydroxyl residues, is a poly(ethylene glycol) having a structure H—(OCH₂—CH₂)_(n)—OH  wherein n is an integer in the range of 2 to about 500; and (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (B) optionally, a water-dispersible polymer blended with said sulfopolyester; and (C) optionally, a water-nondispersible polymer blended with said sulfopolyester with the proviso that said blend is an immiscible blend.
 2. The fiber according to claim 1 in which said dicarboxylic acids are selected from the group consisting of aliphatic diacids, cycloaliphatic dicarboxylic acids, aromatic dicarboxylic acids, and combinations thereof.
 3. The fiber according to claim 2 in which said dicarboxylic acids are selected from succinic, glutaric, adipic, azelaic, sebacic, fumaric, maleic, itaconic, 1,3-cyclohexane dicarboxylic, 1,4-cyclohexanedicarboxylic, diglycolic, 2,5-norbornanedicarboxylic, phthalic, terephthalic, 1,4-naphthalenedicarboxylic, 2,5-naphthalenedicarboxylic, 2,6-naphthalenedicarboxylic, 2,7-naphthalenedicarboxylic, diphenic, 4,4′-oxydibenzoic, 4,4′-sulfonyldibenzoic, isophthalic, and combinations thereof.
 4. The fiber according to claim 3 in which said sulfomonomer is a metal sulfonate salt of a sulfophthalic acid, sulfoterephthalic acid, sulfoisophthalic acid, or combinations thereof.
 5. The fiber according to claim 4 in which said diol residues are selected from ethylene glycol, diethylene glycol, triethylene glycol, poly(ethylene) glycols, propylene glycol, 1,3-propanediol, 2,4-dimethyl-2-ethylhexane-1,3-diol, 2,2-dimethyl-1,3-propanediol, 2-ethyl-2-butyl-1,3-propanediol, 2-ethyl-2-isobutyl-1,3-propanediol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2,4-trimethyl-1,6-hexanediol, thiodiethanol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4,4-tetramethyl-1,3-cyclobutanediol, p-xylylenediol, and combinations thereof.
 6. The fiber according to claim 5 in which said branching monomer is 1,1,1-trimethylol propane, 1,1,1-trimethylolethane, glycerin, pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol, trimellitic anhydride, pyromellitic dianhydride, dimethylol propionic acid, or combinations thereof.
 7. A water-dispersible fiber comprising: A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfpolyester comprising: (i) about 50 to about 96 mole % of a residue of isophthalic acid, based on the total acid residues; (ii) about 4 to about 30 mole %, based on the total acid residues, of a residue of sodiosulfoisophthalic acid; (iii) one or more diol residues wherein at least 25 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure H—(OCH₂—CH₂)_(n)—OH  wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (B) optionally, a first water-dispersible polymer blended with said sulfopolyester; and (C) optionally, a water-nondispersible polymer blended with said sulfopolyester to form a blend with the proviso that said blend is an immiscible blend.
 8. The fiber according to claim 7 comprising a first water-dispersible polymer blended with said sulfopolyester.
 9. The fiber according to claim 7 comprising a water-nondispersible polymer blended to form a blend in which said blend is an immiscible blend.
 10. The fiber of claim 7 in which said residue of isophthalic acid is about 75 to about 96 mole % and said diol residue is about 25 to about 95 mole % of a residue of diethylene glycol.
 11. The fiber of claim 10 in which said fiber is a staple, monofilament, or a multifilament fiber and has a shaped cross-section.
 12. A fibrous article comprising the fiber of claim
 11. 13. The fibrous article of claim 12 in which said article is selected from a yarn, fabric, melt blown web, spunbonded web, nonwoven fabric, and combinations thereof.
 14. The fibrous article of claim 12 in which said article comprises one or more layers of fibers.
 15. The fibrous article of claim 14 in which said article is a wipe, gauze, tissue, diaper, fiber-containing cleaning product, laminating binder, sanitary napkin, panty liner, tampon, training pants, incontinent product, bandage, or surgical dressing.
 16. The fibrous article of claim 15 in which said article is flushable.
 17. The fibrous article of claim 7 further comprising a water-dispersible film in which said water-dispersible film comprises a second water-dispersible polymer.
 18. The fibrous article of claim 17 in which said second water-dispersible polymer comprises an additional sulfopolyester, said additional sulfopolyester comprising: (i) about 50 to about 96 mole % of a residue of isophthalic acid, based on the total acid residues; (ii) about 4 to about 30 mole %, based on the total acid residues, of a residue of sodiosulfoisophthalic acid; (iii) one or more diol residues wherein at least 15 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure H—(OCH₂—CH₂)_(n)—OH  wherein n is an integer in the range of 2 to about 500; and (iv) 0 to about 20 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof.
 19. The fibrous article of claim 18 in which said isophthalic acid residue of said additional sulfopolyester is about 75 to about 96 mole % and said diol residue of said additional sulfopolyester is about 25 to about 95 mole % of a residue of diethylene glycol.
 20. The fibrous article of claim 18 further comprising a powder in which said powder comprises a third water-dispersible polymer.
 21. The fibrous article of claim 18 in which said article is a wipe, gauze, tissue, diaper, fiber-containing cleaning product, sanitary napkin, panty liner, tampon, training pants, incontinent product, bandage, or surgical dressing.
 22. The fibrous article of claim 21 in which said article is flushable.
 23. A process for water-dispersible fibers comprising: I. providing a water-dispersible polymer composition comprising (A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfopolyester comprising: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more metal sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (iii) one or more diol residues wherein at least 20 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure H—(OCH2—CH₂)_(n)—OH  wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (B) optionally, a water-dispersible polymer blended with said sulfopolyester; and (C) optionally, a water-nondispersible polymer blended with said sulfopolyester to form a blend with the proviso that said blend is an immiscible blend. II. heating said polymer composition to a temperature above its flow point; and III. melt spinning filaments.
 24. A process for water-dispersible, nonwoven fabric comprising I. providing a water-dispersible polymer composition comprising (A) a sulfopolyester having a glass transistion temperature (Tg) of at least 25° C., said sulfopolyester comprising: (i) residues of one or more dicarboxylic acids; (ii) about 4 to about 40 mole %, based on the total repeating units, of residues of at least one sulfomonomer having 2 functional groups and one or more metal sulfonate groups attached to an aromatic or cycloaliphatic ring wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (iii) one or more diol residues wherein at least 20 mole %, based on the total diol residues, is a poly(ethylene glycol) having a structure H—(OCH2—CH2)_(n)—OH  wherein n is an integer in the range of 2 to about 500; (iv) 0 to about 25 mole %, based on the total repeating units, of residues of a branching monomer having 3 or more functional groups wherein said functional groups are hydroxyl, carboxyl, or a combination thereof; (B) optionally, a water-dispersible polymer blended with said sulfopolyester; and (C) optionally, a water-nondispersible polymer blended with said sulfopolyester to form a blend with the proviso that said blend is an immiscible blend. II. heating said polymer composition to a temperature above its flow point; III. melt spinning filaments; and IV. overlapping and collecting said filaments of Step III to form a nonwoven web. 